Downlink flow control

ABSTRACT

Systems and methodologies are described that facilitate providing flow control feedback for controlling downlink data transmission rates. Various schemes can be utilized to send the flow control feedback from an access terminal to a base station. For example, a control PDU (e.g., MAC control PDU, PDCP control PDU) can be generated based upon a level of resource utilization of the access terminal, and sent to the base station for controlling the downlink data transmission rate. Following this example, a type of control PDU, a value included within the control PDU, etc. can be selected as a function of the level of resource utilization. By way of another illustration, a CQI report that includes a value selected as a function of the level of resource utilization associated with the access terminal can be generated and transmitted to the base station for controlling the downlink data transmission rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/338,969, entitled “DOWNLINK FLOW CONTROL,” filedDec. 18, 2008, which claimed the benefit of and priority to U.S.Provisional Patent Application No. 61/015,987, entitled “METHODS ANDAPPARATUSES FOR DOWNLINK FLOW CONTROL,” filed Dec. 21, 2007, and U.S.Provisional Patent Application No. 61/036,407, entitled “METHODS ANDAPPARATUSES FOR DOWNLINK FLOW CONTROL UTILIZING CHANNEL QUALITYINDICATOR (CQI),” filed Mar. 13, 2008. The entireties of theaforementioned applications are herein incorporated by reference.

BACKGROUND

I. Field

The following description relates generally to wireless communications,and more particularly to providing feedback related to resourceutilization of an access terminal that can be leveraged for downlinkflow control in a Long Term Evolution (LTE) based wireless communicationsystem.

II. Background

Wireless communication systems are widely deployed to provide varioustypes of communication; for instance, voice and/or data can be providedvia such wireless communication systems. A typical wirelesscommunication system, or network, can provide multiple users access toone or more shared resources (e.g., bandwidth, transmit power, . . . ).For instance, a system can use a variety of multiple access techniquessuch as Frequency Division Multiplexing (FDM), Time DivisionMultiplexing (TDM), Code Division Multiplexing (CDM), OrthogonalFrequency Division Multiplexing (OFDM), and others.

Generally, wireless multiple-access communication systems cansimultaneously support communication for multiple access terminals. Eachaccess terminal can communicate with one or more base stations viatransmissions on forward and reverse links. The forward link (ordownlink) refers to the communication link from base stations to accessterminals, and the reverse link (or uplink) refers to the communicationlink from access terminals to base stations. This communication link canbe established via a single-in-single-out, multiple-in-single-out or amultiple-in-multiple-out (MIMO) system.

MIMO systems commonly employ multiple (N_(T)) transmit antennas andmultiple (N_(R)) receive antennas for data transmission. A MIMO channelformed by the N_(T) transmit and N_(R) receive antennas can bedecomposed into N_(S) independent channels, which can be referred to asspatial channels, where N_(S)≦{N_(T), N_(R)}. Each of the N_(S)independent channels corresponds to a dimension. Moreover, MIMO systemscan provide improved performance (e.g., increased spectral efficiency,higher throughput and/or greater reliability) if the additionaldimensionalities created by the multiple transmit and receive antennasare utilized.

MIMO systems can support various duplexing techniques to divide forwardand reverse link communications over a common physical medium. Forinstance, frequency division duplex (FDD) systems can utilize disparatefrequency regions for forward and reverse link communications. Further,in time division duplex (TDD) systems, forward and reverse linkcommunications can employ a common frequency region so that thereciprocity principle allows estimation of the forward link channel fromreverse link channel.

Wireless communication systems oftentimes employ one or more basestations that provide a coverage area. A typical base station cantransmit multiple data streams for broadcast, multicast and/or unicastservices, wherein a data stream may be a stream of data that can be ofindependent reception interest to an access terminal. An access terminalwithin the coverage area of such base station can be employed to receiveone, more than one, or all the data streams carried by the compositestream. Likewise, an access terminal can transmit data to the basestation or another access terminal.

Access terminals typically support multimedia and many differentapplications running concurrently (e.g., email, voice, video, . . . ).Long Term Evolution (LTE) based environments can also enable supportingvery high data rates (e.g., data can be sent over the downlink at rateson the order of 100 Mbit/s, 300 Mbit/s, . . . ). Further, eachapplication can demand a certain amount of resources from the accessterminal (e.g., processing power, buffers, battery power, . . . ).Moreover, the amount of resources needed at a given time can be dynamic.

It is to be appreciated that access terminals can be designed to handlethe sum of maximum instantaneous requirements of all applications thatcan be effectuated therewith. To maintain costs associated with accessterminals at a reasonable level, however, access terminals can bedesigned to handle common load conditions rather than peak instantaneousrequirements, which can be significantly larger than the common load.For example, the peak instantaneous requirements can occur when allapplications supported by an access terminal happen to launchconcurrently while the access terminal is simultaneously receiving dataat the peak rate via the downlink. Thus, the access terminal can beprovisioned to handle the peak rate for a short duration of time ratherthan being able to sustain operability at the peak rate for an extendedperiod of time, which in turn can significantly reduce costs associatedwith the access terminal.

If an access terminal is not over-dimensioned (e.g., designed toaccommodate common load conditions rather than peak instantaneousrequirements for an extended period of time, . . . ), it can run low inresources. When availability of resources of an access terminal is low,the access terminal can attempt to reduce its load. However, LTEcurrently fails to support providing feedback from the access terminalto the base station when the access terminal is experiencing lowresources. For example, if the base station is sending data to theaccess terminal at a high speed (e.g., 100 Mbit/s, . . . ) for anextended period of time, the access terminal can be unable to handleprocessing of such downlink data and/or the buffer can become full;meanwhile, the access terminal can lack a manner by which it can notifythe base station to reduce the downlink transmission rate.

In UMTS Terrestrial Radio Access Network (UTRAN), flow control issupported in Radio Link Control (RLC). According to an illustration, anaccess terminal operating in UTRAN can set a transmitting window size ofa base station for flow control purposes; thus, when the access terminalis congested, the access terminal can collapse the transmitting windowsize of the base station. The aforementioned flow control techniqueutilized in UTRAN, however, is not applicable to LTE since the RLC hasbeen redefined in LTE. Accordingly, utilization of the RLC for flowcontrol is inoperable in LTE.

SUMMARY

The following presents a simplified summary of one or more embodimentsin order to provide a basic understanding of such embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements of allembodiments nor delineate the scope of any or all embodiments. Its solepurpose is to present some concepts of one or more embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

In accordance with one or more embodiments and corresponding disclosurethereof, various aspects are described in connection with facilitatingproviding of flow control feedback for controlling downlink datatransmission rates. Various schemes can be utilized to send the flowcontrol feedback from an access terminal to a base station. For example,a control PDU (e.g., MAC control PDU, PDCP control PDU) can be generatedbased upon a level of resource utilization of the access terminal, andsent to the base station for controlling the downlink data transmissionrate. Following this example, a type of control PDU, a value includedwithin the control PDU, etc. can be selected as a function of the levelof resource utilization. By way of another illustration, a CQI reportthat includes a value selected as a function of the level of resourceutilization associated with the access terminal can be generated andtransmitted to the base station for controlling the downlink datatransmission rate.

According to related aspects, a method that facilitates providingdownlink flow control in a wireless communication environment isdescribed herein. The method can include monitoring resource useassociated with an access terminal. Further, the method can comprisegenerating a control protocol data unit (PDU) based upon the resourceuse associated with the access terminal. Moreover, the method caninclude sending the control PDU to a base station to manage a downlinkdata transmission rate.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus can include a memory that retainsinstructions related to generating a control protocol data unit (PDU)based upon detected resource use associated with an access terminal, andtransmitting the control PDU to a base station to control a downlinkdata transmission rate. Further, the wireless communications apparatuscan include a processor, coupled to the memory, configured to executethe instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus thatenables providing flow control feedback to a base station using controlprotocol data units (PDUs) in a wireless communication environment. Thewireless communications apparatus can include means for trackingresource utilization associated with an access terminal. Moreover, thewireless communications apparatus can include means for yielding acontrol PDU as a function of the resource utilization associated withthe access terminal. Further, the wireless communications apparatus cancomprise means for transmitting the control PDU to a base station tocontrol a downlink data transmission rate.

Still another aspect relates to a computer program product that cancomprise a computer-readable medium. The computer-readable medium caninclude code for generating a control protocol data unit (PDU) basedupon detected resource use associated with an access terminal. Further,the computer-readable medium can include code for transmitting thecontrol PDU to a base station to control a downlink data transmissionrate.

According to other aspects, a method that facilitates providing downlinkflow control in a wireless communication environment is describedherein. The method can include detecting a level of resource utilizationassociated with an access terminal. Further, the method can includegenerating a channel quality indicator (CQI) report that includes avalue selected as a function of the level of resource utilizationassociated with the access terminal. Moreover, the method can includetransmitting the CQI report that includes the selected value to a basestation to control a downlink data transmission rate.

Yet another aspect relates to a wireless communications apparatus thatcan include a memory that retains instructions related to detecting alevel of resource utilization associated with an access terminal,generating a channel quality indicator (CQI) report that includes avalue selected as a function of the level of resource utilizationassociated with the access terminal, and transmitting the CQI reportthat includes the selected value to a base station to control a downlinkdata transmission rate. Further, the wireless communications apparatuscan comprise a processor, coupled to the memory, configured to executethe instructions retained in the memory.

Another aspect relates to a wireless communications apparatus thatenables yielding flow control feedback to a base station using channelquality indicator (CQI) reports in a wireless communication environment.The wireless communications apparatus can include means for detectingresource utilization associated with an access terminal. Moreover, thewireless communications apparatus can comprise means for yielding a CQIreport that includes a value selected as a function of the resourceutilization associated with the access terminal. Further, the wirelesscommunications apparatus can include means for sending the CQI reportthat includes the selected value to a base station to control a downlinkdata transmission rate.

Still another aspect relates to a computer program product that cancomprise a computer-readable medium. The computer-readable medium caninclude code for detecting a level of resource utilization associatedwith an access terminal. Further, the computer-readable medium caninclude code for generating a channel quality indicator (CQI) reportthat includes a value selected as a function of the level of resourceutilization associated with the access terminal. Moreover, thecomputer-readable medium can include code for transmitting the CQIreport that includes the selected value to a base station to control adownlink data transmission rate.

According other aspects, a method that facilitates controlling adownlink data transmission rate for an access terminal based upon flowcontrol feedback from the access terminal in a wireless communicationenvironment is described herein. The method can include receiving acontrol protocol data unit (PDU) that provides flow control feedbackfrom an access terminal. Further, the method can comprise analyzing thecontrol PDU to recognize the flow control feedback. Moreover, the methodcan include adjusting a downlink data transmission rate for the accessterminal based upon the flow control feedback provided by the controlPDU.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus can include a memory that retainsinstructions related to receiving a channel quality indicator (CQI)report that includes a value corresponding to flow control feedback froman access terminal, evaluating the value included in the CQI report todetermine the flow control feedback, and adjusting a downlink datatransmission rate for the access terminal based upon the flow controlfeedback provided by the CQI report. Further, the wirelesscommunications apparatus can include a processor, coupled to the memory,configured to execute the instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus thatenables altering a downlink data transmission rate employing flowcontrol feedback in a wireless communication environment. The wirelesscommunications apparatus can include means for obtaining a channelquality indicator (CQI) report that includes a value corresponding toflow control feedback from an access terminal. Moreover, the wirelesscommunications apparatus can include means for analyzing the valueincluded in the CQI report to identify the flow control feedback.Further, the wireless communications apparatus can include means formodifying a downlink data transmission rate for the access terminalbased upon the flow control feedback provided by the CQI report.

Still another aspect relates to a computer program product that cancomprise a computer-readable medium. The computer-readable medium caninclude code for obtaining a control protocol data unit (PDU) thatprovides flow control feedback from an access terminal. Moreover, thecomputer-readable medium can include code for evaluating the control PDUto identify the flow control feedback. Further, the computer-readablemedium can include code for altering a downlink data transmission ratefor the access terminal based upon the flow control feedback provided bythe control PDU.

Toward the accomplishment of the foregoing and related ends, the one ormore embodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth herein detail certain illustrativeaspects of the one or more embodiments. These aspects are indicative,however, of but a few of the various ways in which the principles ofvarious embodiments can be employed and the described embodiments areintended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a wireless communication system inaccordance with various aspects set forth herein.

FIG. 2 is an illustration of an example system that utilizes downlinkflow control in a wireless communication environment.

FIG. 3 is an illustration of an example system that utilizes controlPDUs for providing flow control feedback in a wireless communicationenvironment.

FIG. 4 is an illustration of an example system that employs ChannelQuality Indicator (CQI)-based downlink flow control in a wirelesscommunication environment.

FIG. 5 is an illustration of an example timing diagram that depictsperiodic flow control reporting that utilizes CQI values to providefeedback from an access terminal to a base station.

FIG. 6 is an illustration of an example comparison of a measured CQIvalue to a resource dependent CQI value.

FIG. 7 is an illustration of an example methodology that facilitatesproviding downlink flow control in a wireless communication environment.

FIG. 8 is an illustration of another example methodology thatfacilitates providing downlink flow control in a wireless communicationenvironment.

FIG. 9 is an illustration of an example methodology that facilitatescontrolling a downlink data transmission rate for an access terminalbased upon flow control feedback from the access terminal in a wirelesscommunication environment.

FIG. 10 is an illustration of an example methodology that facilitatesutilizing flow control feedback to manage a downlink data transmissionrate for an access terminal in a wireless communication environment.

FIG. 11 is an illustration of an example access terminal that generatesflow control feedback in a wireless communication system.

FIG. 12 is an illustration of an example system that utilizes obtainedflow control feedback to manage a downlink data transmission rate in awireless communication environment.

FIG. 13 is an illustration of an example wireless network environmentthat can be employed in conjunction with the various systems and methodsdescribed herein.

FIG. 14 is an illustration of an example system that enables providingflow control feedback to a base station using control protocol dataunits (PDUs) in a wireless communication environment.

FIG. 15 is an illustration of an example system that enables yieldingflow control feedback to a base station using channel quality indicator(CQI) reports in a wireless communication environment.

FIG. 16 is an illustration of an example system that enables adjusting adownlink data transmission rate utilizing flow control feedback in awireless communication environment.

FIG. 17 is an illustration of an example system that enables altering adownlink data transmission rate employing flow control feedback in awireless communication environment.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component can be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component can be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components can communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

The techniques described herein can be used for various wirelesscommunication systems such as code division multiple access (CDMA), timedivision multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier-frequency division multiple access (SC-FDMA) and other systems.The terms “system” and “network” are often used interchangeably. A CDMAsystem can implement a radio technology such as Universal TerrestrialRadio Access (UTRA), CDMA2000, etc. UTRA includes Wideband-CDMA (W-CDMA)and other variants of CDMA. CDMA2000 covers IS-2000, IS-95 and IS-856standards. A TDMA system can implement a radio technology such as GlobalSystem for Mobile Communications (GSM). An OFDMA system can implement aradio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband(UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunication System (UMTS). 3GPP Long Term Evolution (LTE) is anupcoming release of UMTS that uses E-UTRA, which employs OFDMA on thedownlink and SC-FDMA on the uplink.

Single carrier frequency division multiple access (SC-FDMA) utilizessingle carrier modulation and frequency domain equalization. SC-FDMA hassimilar performance and essentially the same overall complexity as thoseof an OFDMA system. A SC-FDMA signal has lower peak-to-average powerratio (PAPR) because of its inherent single carrier structure. SC-FDMAcan be used, for instance, in uplink communications where lower PAPRgreatly benefits access terminals in terms of transmit power efficiency.Accordingly, SC-FDMA can be implemented as an uplink multiple accessscheme in 3GPP Long Term Evolution (LTE) or Evolved UTRA.

Furthermore, various embodiments are described herein in connection withan access terminal. An access terminal can also be called a system,subscriber unit, subscriber station, mobile station, mobile, remotestation, remote terminal, mobile device, user terminal, terminal,wireless communication device, user agent, user device, or userequipment (UE). An access terminal can be a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, computing device,or other processing device connected to a wireless modem. Moreover,various embodiments are described herein in connection with a basestation. A base station can be utilized for communicating with accessterminal(s) and can also be referred to as an access point, Node B,Evolved Node B (eNodeB) or some other terminology.

Various aspects or features described herein can be implemented as amethod, apparatus, or article of manufacture using standard programmingand/or engineering techniques. The term “article of manufacture” as usedherein is intended to encompass a computer program accessible from anycomputer-readable device, carrier, or media. For example,computer-readable media can include but are not limited to magneticstorage devices (e.g., hard disk, floppy disk, magnetic strips, etc.),optical disks (e.g., compact disk (CD), digital versatile disk (DVD),etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick,key drive, etc.). Additionally, various storage media described hereincan represent one or more devices and/or other machine-readable mediafor storing information. The term “machine-readable medium” can include,without being limited to, wireless channels and various other mediacapable of storing, containing, and/or carrying instruction(s) and/ordata.

Referring now to FIG. 1, a wireless communication system 100 isillustrated in accordance with various embodiments presented herein.System 100 comprises a base station 102 that can include multipleantenna groups. For example, one antenna group can include antennas 104and 106, another group can comprise antennas 108 and 110, and anadditional group can include antennas 112 and 114. Two antennas areillustrated for each antenna group; however, more or fewer antennas canbe utilized for each group. Base station 102 can additionally include atransmitter chain and a receiver chain, each of which can in turncomprise a plurality of components associated with signal transmissionand reception (e.g., processors, modulators, multiplexers, demodulators,demultiplexers, antennas, etc.), as will be appreciated by one skilledin the art.

Base station 102 can communicate with one or more access terminals suchas access terminal 116 and access terminal 122; however, it is to beappreciated that base station 102 can communicate with substantially anynumber of access terminals similar to access terminals 116 and 122.Access terminals 116 and 122 can be, for example, cellular phones, smartphones, laptops, handheld communication devices, handheld computingdevices, satellite radios, global positioning systems, PDAs, and/or anyother suitable device for communicating over wireless communicationsystem 100. As depicted, access terminal 116 is in communication withantennas 112 and 114, where antennas 112 and 114 transmit information toaccess terminal 116 over a forward link 118 and receive information fromaccess terminal 116 over a reverse link 120. Moreover, access terminal122 is in communication with antennas 104 and 106, where antennas 104and 106 transmit information to access terminal 122 over a forward link124 and receive information from access terminal 122 over a reverse link126. In a frequency division duplex (FDD) system, forward link 118 canutilize a different frequency band than that used by reverse link 120,and forward link 124 can employ a different frequency band than thatemployed by reverse link 126, for example. Further, in a time divisionduplex (TDD) system, forward link 118 and reverse link 120 can utilize acommon frequency band and forward link 124 and reverse link 126 canutilize a common frequency band.

Each group of antennas and/or the area in which they are designated tocommunicate can be referred to as a sector of base station 102. Forexample, antenna groups can be designed to communicate to accessterminals in a sector of the areas covered by base station 102. Incommunication over forward links 118 and 124, the transmitting antennasof base station 102 can utilize beamforming to improve signal-to-noiseratio of forward links 118 and 124 for access terminals 116 and 122.Also, while base station 102 utilizes beamforming to transmit to accessterminals 116 and 122 scattered randomly through an associated coverage,access terminals in neighboring cells can be subject to lessinterference as compared to a base station transmitting through a singleantenna to all its access terminals.

In system 100, access terminals 116, 122 can each monitor theirrespective resource utilization. For instance, resources of accessterminals 116, 122 can include processor cycles, power levels, bufferavailability, bus bandwidth, and so forth. By way of illustration, inLong Term Evolution (LTE), access terminals 116, 122 can handle veryhigh data rates. Due to cost effective implementation, resources ofaccess terminals 116, 122 can run low during a given scenario (e.g.,when a user application is started while access terminal 116, 122 isreceiving data over the downlink at a high rate, . . . ). Accordingly,system 100 can achieve downlink flow control. By monitoring respectiveresource utilization, access terminals 116, 122 can send feedback tobase station 102 requesting reduction in respective downlink datatransmission rate to temporarily mitigate resource requirements for eachrespective access terminal 116, 122. Further, when the resourceutilization level of a particular access terminal 116, 122 returns tonormal (e.g., non-elevated level, below a threshold, . . . ), theparticular access terminal 116, 122 can transmit a request to basestation 102 to resume normal data transmission over the downlink.Accordingly, access terminals 116, 122 can send flow control feedback tobase station 102, and base station 102 can react to the feedback byreducing throughput (e.g., when resource utilization of the respectiveaccess terminal 116, 122 is low, . . . ) and/or increasing thethroughput (e.g., when resource utilization of the respective accessterminal 116, 122 returns to normal, . . . ).

System 100 can leverage a standardized flow control procedure thatallows a resource-limited access terminal (e.g., access terminal 116,access terminal 122, . . . ) to throttle sending of data by base station102, thus enabling base station 102 to beneficially reallocate physicalresources to other access terminals. Downlink flow control as describedherein can yield significant benefits. For example, downlink flowcontrol can provide flexibility for access terminal implementation,which can result in reducing costs associated with access terminals 116,122 (e.g., an access terminal can share certain resources amongapplications to achieve multiplexing gain, . . . ). Further, downlinkflow control can protect access terminals 116, 122 from an overloadscenario. Moreover, downlink flow control can provide an effective meansfor access terminals 116, 122 to cope with a high peak data rate toaverage data rate ratio without over-dimensioning such access terminals116, 122. Downlink flow control can also result in enhancing userexperience (e.g., user applications can launch faster, an accessterminal 116, 122 can invoke flow control to reduce best-effort flowtemporarily when the application is being launched, . . . ).

Referring to FIG. 2, illustrated is a system 200 that utilizes downlinkflow control in a wireless communication environment. System 200includes an access terminal 202 that can transmit and/or receiveinformation, signals, data, instructions, commands, bits, symbols, andthe like. Access terminal 202 can communicate with a base station 204via the forward link and/or reverse link. Base station 204 can transmitand/or receive information, signals, data, instructions, commands, bits,symbols, and the like. Moreover, although not shown, it is contemplatedthat any number of access terminals similar to access terminal 202 canbe included in system 200 and/or any number of base stations similar tobase station 204 can be included in system 200.

Access terminal 202 further includes a resource monitor 206 and a flowcontrol feedback generator 208. Resource monitor 206 can analyzeutilization of resources of access terminal 202. For instance, theresources can relate to processing speed, processor cycles, batterypower, buffer size, bus speed, and so forth. Resource monitor 206 canidentify a congestion level encountered by access terminal 202. Thus,resource monitor 206 can recognize overloading of access terminal 202such that access terminal 202 is unable to handle a current load (e.g.,resource monitor 206 can determine that resources of access terminal 202are insufficient to handle the current traffic received on the downlink,. . . ). By way of illustration, resource monitor 206 can determinewhether resource utilization is above or below a threshold (e.g.,whether or not access terminal 202 is overloaded, . . . ). According toanother example, resource monitor 206 can determine a resourceutilization level (e.g., percentage of use of one or more resources,resource monitor 206 can provide a more granular view of resourceutilization, . . . ).

Flow control feedback generator 208 can employ resource utilizationinformation identified by resource monitor 206 to yield feedback thatcan be sent to base station 204 to alter downlink throughput. By way ofexample, resource monitor 206 can detect an overload condition, andbased thereupon, flow control feedback generator 208 can output flowcontrol feedback, which can be transmitted to base station 204 torequest downlink throughput adjustment. Further, resource monitor 206can recognize that resources of access terminal 202 are not overloaded;hence, flow control feedback generator 208 can yield correspondingfeedback that can be sent to base station 204. Moreover, flow controlfeedback generator 208 can provide feedback as a function ofcapabilities of access terminal 202. The flow control feedback generatedby flow control feedback generator 208 can be utilized to induce changesin downlink throughput allocated by base station 204 to access terminal202.

It is to be appreciated that employment of various types of flow controlfeedback is intended to fall within the scope of the hereto appendedclaims. For instance, the flow control feedback yielded by flow controlfeedback generator 208 can leverage utilization of control protocol dataunits (PDUs). Pursuant to another example, flow control feedbackgenerator 208 can employ Channel Quality Indicator (CQI) reports to sendflow control feedback to base station 204.

Base station 204 can receive the flow control feedback from accessterminal 202 (as well as flow control feedback from any disparate accessterminal(s) (not shown) similar to access terminal 202 served by basestation 204). Base station 204 can include a feedback analyzer 210 thatreviews the obtained flow control feedback. Feedback analyzer 210 candecode the flow control feedback to recognize whether access terminal202 has requested adjustment of downlink throughput. According toanother example, feedback analyzer 210 can evaluate the flow controlfeedback to identify an amount of downlink throughput adjustmentrequested by access terminal 202. Pursuant to a further example,feedback analyzer 210 can recognize capabilities associated with accessterminal 202 based upon review of the flow control feedback from accessterminal 202.

Further, base station 204 can include a downlink scheduler 212 thatalters downlink throughput allotted to access terminal 202 based uponthe evaluation of the flow control feedback yielded by flow controlfeedback generator 208 of access terminal 202. Similarly, downlinkscheduler 212 can adjust downlink throughput allocated to any disparate,served access terminal(s). For instance, flow control can be sticky suchthat a command received by base station 204 can be utilized to retaindownlink throughput level allocated by downlink scheduler 212 for accessterminal 202 as long as no other command is received from accessterminal 202 (e.g., the downlink throughput remains in an updated stateuntil obtaining a subsequent command, . . . ). By way of anotherexample, flow control can be temporary such that a command is valid fora period of time, and downlink scheduler 212 can adjust the downlinkthroughput to a default rate (e.g., full rate, . . . ) upon expirationof the period of time associated with the command (e.g., the downlinkthroughput returns to an original state from the updated state afterexpiration of the period of time, . . . ). Moreover, it is contemplatedthat flow control can be sticky or temporary depending on an applicationbeing effectuated by access terminal 202 and/or base station 204.

According to an example, it is contemplated that flow control feedbackgenerator 208 (or access terminal 202 generally) can control a rate offlow control. Following this example, to limit utilization of the uplinkfor sending flow control commands, upper layers can configure a timerthat can disallow access terminal 202 from sending a flow controlcommand prior to expiration of the timer (e.g., creating a minimum timeduration between adjacent flow control command transmissions by accessterminal 202, . . . ). Pursuant to a further illustration, flow controlfeedback generator 208 can allow a maximum number of flow controlcommands to be sent from access terminal 202 per unit of time.

Various flow control schemes are described herein. It is to beappreciated that any of these schemes can be employed, a combination oftwo or more of these schemes can be utilized, and so forth. Anillustration of a flow control scheme that can be utilized by system 200leverages employing hybrid automatic repeat request (HARQ) negativeacknowledgements (NACKs). In this scheme, when resources of accessterminal 202 run low (e.g., as determined by resource monitor 206, . . .), flow control feedback generator 208 can generate and send a HARQ NACKon the uplink to NACK downlink HARQ packets that are correctly received.By NACKing a first HARQ transmission regardless of whether the packet iscorrectly received, a downlink throughput can be reduced by half.Further, by NACKing a first HARQ and a second HARQ transmission for eachpacket regardless whether the packet is correctly received, the downlinkthroughput can be reduced to one-third. It is contemplated that anynumber of NACKs can be sent by flow control feedback generator 208 inresponse to each received packet. Further, it is to be appreciated thatthe claimed subject matter is not limited to the aforementioned example.

Turning to FIG. 3, illustrated is a system 300 that utilizes controlPDUs for providing flow control feedback in a wireless communicationenvironment. System 300 includes access terminal 202, which can furthercomprise resource monitor 206 and flow control feedback generator 208.System 300 can also include base station 204, which can further comprisefeedback analyzer 210 and downlink scheduler 212. Flow control feedbackgenerator 208 can further include a control PDU formatter 302 thatgenerates a control PDU as a function of resource utilization fortransmission to base station 204. Control PDU formatter 302, forexample, can select a type of control PDU from a set of possible controlPDU types, set a value within the control PDU, a combination thereof,and so forth. Further, feedback analyzer 210 of base station 204 canfurther include a control PDU evaluator 304 that can recognize a type ofa received control PDU, a value within the received control PDU, acombination thereof, etc. Moreover, control PDU evaluator 304 candetermine a downlink data rate change to effectuate (e.g., with downlinkscheduler 212, . . . ) as a function of the recognized type, value,combination thereof, and the like. It is contemplated that system 300can utilize a Media Access Control (MAC) control PDU, a Packet DataConvergence Protocol (PDCP) control PDU, a combination thereof, etc. forproviding feedback from access terminal 202 to base station 204;however, the claimed subject matter is not so limited.

MAC-based flow control can be employed by system 300. For example, MACcontrol PDU type can be utilized to provide feedback concerningavailability and/or utilization of resources of access terminal 202.Pursuant to an illustration, two types of MAC control PDUs (e.g., type 1MAC control PDU and type 2 MAC control PDU, . . . ) can be defined toyield flow control feedback. Accordingly, when resource monitor 206recognizes that resources of access terminal 202 run low (e.g., highlevel of resource utilization, . . . ), control PDU formatter 302 canselect a first type of MAC control PDU (e.g., type 1 MAC control PDU, .. . ) that can be sent to base station 204 indicating that its resourcesare low. Further, when resource monitor 206 identifies that resourceutilization for access terminal 202 is back to normal, control PDUformatter 302 can choose a second type of MAC control PDU (e.g., type 2MAC control PDU, . . . ) that can be transmitted to base station 204indicating that its resource utilization is back to normal.

In response to the MAC control PDU type detected by control PDUevaluator 304, reaction by base station 204 can be effectuated.Following the above example, when control PDU evaluator 304 recognizesthat access terminal 202 sent a type 1 MAC control PDU, downlinkscheduler 212 can react by reducing downlink data flow for accessterminal 202. Moreover, when control PDU evaluator 304 determines thataccess terminal 202 transmitted a type 2 MAC control PDU, downlinkscheduler 212 can react by increasing the downlink data flow for accessterminal 202.

Below are additional example MAC-based flow control schemes. In theseschemes, base station 204 can have control of which downlink flow(s) tomodulate. For instance, alteration of rate(s) of downlink flow(s) can bebased upon Quality of Service (QoS) attributes of the flows (e.g., flowswith prioritized bit rate (PBR) configured typically should not be flowcontrolled, . . . ). Further, while the examples herein describe usingMAC-based flow control for access terminal 202 to control a downlinkrate, it is also envisioned that such flow control can apply topeer-to-peer links where a transmitter and a receiver can both be accessterminals; however, the claimed subject matter is not so limited.Moreover, flow control can be applicable on an uplink using unscheduledchannels.

According to an illustration, an on-off MAC-based flow control schemecan be employed by system 300. In this scheme, a type 1 MAC control PDUcan include a binary value (e.g., either ‘0’ or ‘1’), which can be setby control PDU formatter 302 and deciphered by control PDU evaluator 304(e.g., one type of MAC control PDU can be defined to be employed withthe on-off MAC-based flow control scheme, . . . ). When resources ofaccess terminal 202 run low (e.g., resource utilization above athreshold, . . . ), control PDU formatter 302 can set the binary valueof the type 1 MAC control PDU to ‘0’; thereafter, this type 1 MACcontrol PDU with the binary value set to ‘0’ can be sent to base station204. When base station 204 receives this MAC control PDU, control PDUevaluator 304 can recognize that the binary value is set to ‘0’.Further, control PDU evaluator 304 can control downlink scheduler 212 tostop transmitting downlink data to access terminal 202 (except for flowsconfigured with a prioritized bit rate (PBR)). Similarly, when theresource utilization of access terminal 202 returns to normal (e.g.,resource utilization below a threshold, . . . ), control PDU formatter302 can generate a type 1 MAC control PDU with a binary value ‘1’, whichcan be sent to base station 204. When base station 204 receives this MACcontrol PDU, control PDU evaluator 304 can recognize that the binaryvalue is set to ‘1’. Further, control PDU evaluator 304 can causedownlink scheduler 212 to resume downlink data transmission to accessterminal 202.

By way of another example, an up-down MAC-based flow control scheme canbe leveraged by system 300. Two types of MAC control PDUs (e.g., type 1and type 2, . . . ) can be defined for use with this up-down scheme. Inthis scheme, the type 1 MAC control PDU can carry an integer k between 0and N, where N can be an integer greater than or equal to k. Control PDUformatter 302 can use the MAC control PDU to module the downlink datarate. Assuming that resource monitor 206 computes an average downlinkdata rate experienced by access terminal 202 in a given time window tobe q, then q*(k/N) can be the downlink data rate preferred by accessterminal 202. Base station 204 can also estimate an average downlinkdata rate for access terminal 202 as being q′. The estimate effectuatedby base station 204 can be based on an amount of data served to accessterminal 202 (e.g., as determined from downlink scheduler 212, . . . )in a past given window (e.g., which may or may not differ from thewindow employed by access terminal 202, . . . ). The estimates yieldedby access terminal 202 and base station 204 can, but need not, match(e.g., which can be sufficient for purposes of flow control, . . . ). Anadvantage associated with the foregoing is a limited need forstandardization in order to support such features. Pursuant to furtherillustration, when base station 204 receives the type 1 MAC control PDUfrom access terminal 202, control PDU evaluator 304 can adjust thedownlink data rate yielded by downlink scheduler 212 for access terminal202 to be q′*(k/N). It is contemplated that the above data ratesdescribed herein with respect to the up-down MAC-based flow controlscheme can refer to an aggregated downlink data rate for all flowswithout a PBR configured. Moreover, when resource monitor 206 determinesthat access terminal 202 can tolerate receiving a higher data rate,control PDU formatter 302 can yield a type 2 MAC control PDU thatincludes a value k to indicate that a desired throughput is q*(1+k/N).The type 2 MAC control PDU can be sent from access terminal 202 to basestation 204, and control PDU evaluator 304 can analyze the value of kincorporated therein and adapt an average downlink data rate for accessterminal 202 to be q′(1+k/N). The up-down MAC-based flow control schemeenables communication between access terminal 202 and base station 204with a high granularity as to a congestion level experienced by accessterminal 202, which in turn can smooth a transition from congestion tonon-congestion for access terminal 202.

According to a further example, a scaled access terminal capabilityMAC-based flow control scheme can be implemented by system 300. Thescaled access terminal capability MAC-based flow control scheme enablesscaling downlink data rates based upon maximum capabilities of accessterminal 202. In this scheme, a type 1 MAC control PDU can carry aninteger between 0 and N. When resources of access terminal 202 run low(e.g., as recognized by resource monitor 206, . . . ), control PDUformatter 302 can yield a type 1 MAC control PDU for transmission with avalue set to k, where q*(k/N) is an updated maximum data rate to besupported by capabilities of access terminal 202 and q is a previousmaximum data rate supported by capabilities of access terminal 202 asindicated in prior access terminal capability signaling (e.g., asprovided in a previously transmitted MAC control PDU sent by accessterminal 202, . . . ). When base station 204 receives the type 1 MACcontrol PDU, control PDU evaluator 304 can adjust a downlink data rateemployed by downlink scheduler 212 for access terminal 202 as if amaximum data rate supported by capabilities of access terminal 202 areequal to q*(k/N). Note that, in this case, access terminal 202 and basestation 204 share a value of q since it was previously signaled byaccess terminal 202. Further, when access terminal 202 can toleratereceiving a higher data rate (e.g., as identified by resource monitor206, . . . ), control PDU formatter 302 can generate a type 2 MACcontrol PDU, which can be sent to base station 204. This type 2 MACcontrol PDU can include a value k to indicate to base station 204 thatthe desired throughput is q(1+k/N). Control PDU evaluator 304 canthereafter adapt an average downlink data rate employed by downlinkscheduler 212 for access terminal 202 to be q(1+k/N). Accordingly,downlink scheduler 212 can consider capabilities of access terminal 202,which can be enabled by allowing access terminal capabilities to becomevariable in downlink scheduler 212.

Further, PDCP-based flow control can be employed in system 300 wherePDCP control PDUs can be used by access terminal 202 to flow controldownlink rates. These schemes can allow access terminal 202 to flowcontrol each flow independently with high precision. In contrast toutilization of a MAC control PDU for adjusting downlink data rates foran aggregate of downlink flows as described herein, a PDCP control PDUcan be used for altering a downlink rate associated with an individualflow. For instance, if two applications are being executed with accessterminal 202 (e.g., file transfer using file transfer protocol (FTP) andweb browsing, . . . ), each application can be associated with anindividual flow. Further, control PDU formatter 302 can yield a firstPDCP control PDU for controlling a downlink data rate associated withthe first flow (e.g., corresponding to file transfer, . . . ) and/or asecond PDCP control PDU for controlling a downlink data rate associatedwith the second flow (e.g., corresponding to web browsing, . . . ).Thus, pursuant to the above illustration, file transfer can beselectively delayed without impacting a downlink data rate used for webbrowsing.

According to an example, PDCP-based flow control can be employed wherecontrol PDU formatter 302 generates a PDCP control PDU that indicates ahighest PDCP Sequence Number (SN) (e.g., the highest PDCP SN can be setto a value y, . . . ) that can be employed by base station 204 foraccess terminal 202. The PDCP control PDU yielded by control PDUformatter 302 can be sent to base station 204, and control PDU evaluator304 can recognize the value set for the highest PDCP SN incorporated inthe received PDCP control PDU. Additionally or alternatively, the PDCPcontrol PDU can indicate a highest Count-C (e.g., Hyper Frame Number(HFN) plus PDCP SN, . . . ) that can be employed by base station 204 ora part of a Count-C (e.g., lower 16 bits, . . . ). Further, control PDUevaluator 304 can restrict base station 204 from sending PDCP PDUs withSN greater than y until a further PDCP control PDU is received fromaccess terminal 202 allowing transmission of a PDU with a highersequence number.

By way of a further illustration, a maximum number of PDCP PDUs allowedto be transmitted by base station 204 in each Transmission Time Interval(TTI) can be indicated in a PDCP control PDU by control PDU formatter302. Thus, control PDU evaluator 304 can review this PDCP control PDUand restrict the maximum number of PDUs permitted to be sent by basestation 204 to access terminal 202.

Another example PDCP-based flow control scheme that can be employed bysystem 300 leverages use of a PDCP control PDU transferred from accessterminal 202 to base station 204 for switching an associated PDCP beareron and/or off. In a further example PDCP-based flow control scheme, aPDCP control PDU can be utilized to indicate an average rate PDCP atwhich PDCP can transmit, which can be similar to the up-down MAC-basedflow control scheme described herein.

Referring to FIG. 4, illustrated is a system 400 that employs ChannelQuality Indicator (CQI)-based downlink flow control in a wirelesscommunication environment. System 400 includes access terminal 202,which further comprises resource monitor 206 and flow control feedbackgenerator 208. Flow control feedback generator 208 can include aresource based CQI report generator 402 that yields CQI reports that areleveraged to provide flow control feedback to base station 204, whichcan further include feedback analyzer 210 and downlink scheduler 212.Feedback analyzer 210 can include a resource based CQI report evaluator404 that can analyze received CQI reports and perform downlink flowcontrol based upon feedback recognized from the analysis of the receivedCQI reports.

According to an illustration, resource monitor 206 can detect anoverload condition associated with access terminal 202. Based thereupon,resource based CQI report generator 402 can yield a predetermined codeword (hereinafter the flow control code word) in a Channel QualityIndicator that is reserved for flow control. The flow control code wordcan be sent to base station 204. For example, the flow control code wordcan indicate to base station 204 to stop downlink traffic or reduce thedata rate of traffic to access terminal 202. The traffic can be, forexample, non-real time traffic or other types of traffic. Accordingly,access terminal 202 can detect an overload condition (e.g., determinethat resources of access terminal 202 are insufficient to handle thecurrent traffic received on the downlink) and can send flow controlfeedback to base station 204; base station 204 can react to the flowcontrol feedback by reducing the throughput (e.g., when resources ofaccess terminal 202 are low, . . . ) and increasing the throughput(e.g., when resources of access terminal 204 are normal, . . . ).

CQI can be used by access terminal 202 to report a downlink channelquality seen by access terminal 202 to base station 204. Dedicatedresources in the physical layer are provided to report the CQI. Forinstance, 5-10 bits of the Physical Uplink Control Channel (PUCCH) canbe used by access terminal 202 to report CQI to base station 204.According to an example CQI-based flow control scheme, one or more codewords in the CQI code space can be reserved for flow control purposes.Thus, a reserved flow control code word, which can be a predeterminednumber of bits long (e.g., 5 bits long, . . . ), can be generated byresource based CQI report generator 402 and sent to base station 204.According to an illustration, two flow control code words in the CQIcode space can be reserved for flow control purposes (e.g., the reservedvalues can indicate “no flow control” and “flow control”, . . . ).Following this illustration, when resources of access terminal 202 runlow, resource based CQI report generator 402 can yield a CQI report thatincludes the “flow control” value (e.g., a first flow control code word,. . . ), which can be sent to base station 204. Further, when resourceutilization returns to a normal level (e.g., below a threshold, . . . ),resource based CQI report generator 402 can produce a CQI report thatincludes the “no flow control” value (e.g., a second flow control codeword, . . . ).

By way of further example, the number of reserved flow control codewords can be decreased by employing an “OFF” code word without an “ON”code word. The “OFF” command can expire after a period of time. Uponreceipt of the reserved flow control code word (e.g., “OFF” code word, .. . ), resource based CQI report evaluator 404 can initiate a timer,wait a predetermined amount of time and then enable transmission ofnon-real time downlink traffic as scheduled by downlink scheduler 212.For example, since CQI can be allocated at a frequency of 50 Hz orgreater, a single flow control code word that indicates “OFF” can becoupled with a 100 ms timer to provide control with decreased overheadas compared to employment of two or more reserved CQI flow control codewords; however, it is to be appreciated that the claimed subject matteris not so limited.

According to another example where one flow control code word isemployed, the flow control code word can be assigned to be the CQI valuethat indicates the worst channel conditions (e.g., the flow control codeword can be assigned as “00000”, . . . ). An advantage of such anassignment is that when the channel conditions are very poor, it isunlikely that flow control will be needed by access terminal 202.However, it is to be appreciated that any CQI value can be used (e.g.,reserved, . . . ) for flow control code word(s).

When a reserved flow control code word is received by base station 204,resource based CQI report evaluator 404 can adapt the transmission rateemployed by downlink scheduler 212. Pursuant to an example, accessterminal 202 can mitigate sending CQI reports when a request to haltdownlink transmission has been sent since access terminal 202 need notbe employing the channel at such times.

According to another illustration, resource based CQI report generator402 can indicate to reduce or stop non guaranteed bit rate (GBR)traffic, such as best effort traffic or non-real time traffic. Real timetraffic (e.g., voice traffic, . . . ) can still be transmitted by basestation 204. Further, it is noted that any number of flow control codewords that are reserved to indicate flow control feedback can beutilized; however, as the number of flow control code words reserved forflow control feedback increases, the probability that these flow controlcode words can be decoded incorrectly by base station 204 (e.g.,resource based CQI report evaluator 404, . . . ) can also increase.

Pursuant to a further illustration, predetermined CQI reportingintervals can be utilized for flow control reporting. For instance, asubset of CQI reporting intervals can be periodically reserved for flowcontrol reporting. During the flow control reporting intervals, reservedflow control code words (e.g., with predetermined CQI value, . . . ) canbe yielded by resource based CQI report generator 402, sent to basestation 204, and analyzed by resource based CQI report evaluator 404,for example. By way of another illustration, resource dependent CQIvalues can be generated by resource based CQI report generator 402,transmitted to base station 204, and reviewed by resource based CQIreport evaluator 404 to control downlink transmission. Moreover,measured CQI values (e.g., dependent upon channel conditions, . . . )can be sent from access terminal 202 to base station 204 during CQIreporting intervals other than those utilized for flow controlreporting.

Now referring to FIG. 5, illustrated is an example timing diagram 500that depicts periodic flow control reporting that utilizes CQI values toprovide feedback from an access terminal to a base station. As shown,CQI reporting can be periodic. For instance, an access terminal cantransmit a CQI report with substantially any periodicity (e.g., every 2ms, 5 ms, 10 ms, . . . ). As illustrated in diagram 500, every X CQIreporting intervals can be utilized to provide flow control feedback,where X can be substantially any integer (e.g., X can be 10, . . . );the CQI reporting intervals during which flow control feedback istransferred can be referred to as flow control reporting intervals 502.By way of example, at a predetermined time interval (e.g., every 100 ms,. . . ), an access terminal can generate and send a CQI report thatcarries flow control feedback and a base station can interpret such CQIreport as carrying flow control feedback. It is to be appreciated,however, that the claimed subject matter is not limited to this example.

According to an example, the CQI value sent during one of the periodicflow control reporting intervals 502 can be interpreted as follows. Apredetermined CQI value (e.g., reserved value(s) from the set ofpossible CQI values such as a lowest CQI value or an out-of-range value,. . . ) transferred during one of the flow control reporting intervals502 can be interpreted as meaning that “the access terminal is congestedand the base station needs to flow control the downlink now.” Moreover,any other CQI value (e.g., non-reserved value included in the set ofpossible CQI values, . . . ) transferred during one of the flow controlreporting intervals 502 can mean that the access terminal is notcongested, and the reported CQI is the measured CQI that depends only onchannel conditions. An advantage of this flow control technique is thatno special CQI value is reserved for flow control, thereby the CQIresolution is not reduced. Further, the CQI reporting intervals otherthan the flow control reporting intervals (e.g., non-flow CQI reportingintervals 504, . . . ) can be utilized to send measured CQI values,which are dependent upon channel conditions.

By way of a further example, resource dependent CQI values, which differfrom measured CQI values, can be transmitted during flow controlreporting intervals 502 to indicate degree of access terminalcongestion. A resource dependent CQI value is typically less than ameasured CQI value. The measured CQI value is dependent only on thechannel conditions and does not take into account access terminalprocessing limitations. Measured CQI values are reported during non-flowcontrol reporting intervals 504.

The resource dependent CQI value (also referred to as a resourceadjusted CQI value) reduces the measured CQI value to take into accountlimitations in access terminal resources (e.g., processing power, bufferspace, battery life, . . . ). FIG. 6 illustrates an example comparison600 of a measured CQI value 602 to a resource dependent CQI value 604.According to an illustration, when remaining space in a buffer of anaccess terminal is less than a predetermined value, a processor isoperating at more than Y percent of a maximum utilization, or anothermetric indicates that the access terminal is congested, the accessterminal can downwardly adjust measured CQI value 602 to generateresource dependent CQI value 604. Resource dependent CQI value 604 takesinto account resource limitations of the access terminal. Further,resource dependent CQI value 604 can be reported during a flow controlreporting interval (e.g., flow control reporting interval 502 of FIG. 5,. . . ). It is to be noted that if the access terminal is not congested,and flow control is not needed, then the access terminal need not reportresource dependent CQI value 604; instead, the access terminal canreport the measured CQI value 602 at the flow control reportinginterval.

According to an example, the minimum of the resource dependent CQI value604 and the measured CQI value 602 (e.g., channel dependent CQI, . . . )is reported at every flow control reporting interval (e.g., flow controlreporting intervals 502 of FIG. 5, . . . ). At all other CQI reportingintervals (e.g., non-flow control reporting intervals 504 of FIG. 5, . .. ), the measured CQI value 602 (e.g., channel dependent CQI, . . . ) isreported to the base station.

By way of another illustration, when there is no congestion (e.g.,resource utilization below a threshold, . . . ) as monitored by theaccess terminal for a given flow control reporting interval (e.g., flowcontrol reporting intervals 502 of FIG. 5, . . . ), the access terminalreports measured CQI value 602 to the base station. However, when thereis congestion (e.g., resource utilization above a threshold, . . . ),the access terminal reports resource dependent CQI value 604, which istypically lower than measured CQI value 602, during the flow controlreporting interval. At all other CQI reporting intervals (e.g., non-flowcontrol reporting intervals 504 of FIG. 5, . . . ), the measured CQIvalue 602 (e.g., channel dependent CQI, . . . ) is reported to the basestation.

In an example, the base station can receive a 5 bit CQI value from theaccess terminal and map the CQI value to a transfer block size, which isan indicator of a number of bits that can be sent in every TTI. Anadvantage of this embodiment is that the access terminal can indicate adegree of congestion so the base station knows how much to back off thedownlink traffic. In contrast, the periodic CQI scheme that employspredetermined code words described above enables an access terminal toonly say “I'm congested” without informing the base station as to howmuch congestion the access terminal is experiencing.

Referring to FIGS. 7-10, methodologies relating to controlling downlinkdata transmission rates based upon flow control feedback in a wirelesscommunication environment are illustrated. While, for purposes ofsimplicity of explanation, the methodologies are shown and described asa series of acts, it is to be understood and appreciated that themethodologies are not limited by the order of acts, as some acts can, inaccordance with one or more embodiments, occur in different ordersand/or concurrently with other acts from that shown and describedherein. For example, those skilled in the art will understand andappreciate that a methodology could alternatively be represented as aseries of interrelated states or events, such as in a state diagram.Moreover, not all illustrated acts can be required to implement amethodology in accordance with one or more embodiments.

With reference to FIG. 7, illustrated is a methodology 700 thatfacilitates providing downlink flow control in a wireless communicationenvironment. At 702, resource use associated with an access terminal canbe monitored. For example, the resources can relate to processing speed,processor cycles, battery power, buffer size, bus speed, and so forth.The resource use can be compared to a threshold (e.g., determine whetherthe resource use is above or below the threshold, determined whetherresources of the access terminal are sufficient or insufficient tohandle a current traffic level received by the access terminal via thedownlink, . . . ). Additionally or alternatively, the resource use canbe monitored to recognize a percentage of an overall capacity beingcurrently employed (e.g., the percentage can correspond to one or moreresources associated with the access terminal, . . . ).

At 704, a control protocol data unit (PDU) can be generated based uponthe resource use associated with the access terminal. The control PDUcan be generated in accordance with one or more downlink flow controlschemes. For instance, the control PDU can be a Media Access Control(MAC) control PDU, a Packet Data Convergence Protocol (PDCP) controlPDU, a combination thereof, etc.

According to an example MAC-based flow control scheme, a type 1 MACcontrol PDU can be generated when resource use of the access terminal isdetermined to be above a first threshold, and a type 2 MAC control PDUcan be generated when resource use of the access terminal is determinedto be below a second threshold (e.g., the first threshold and the secondthreshold can be the same or different, . . . ). Following this example,the type 1 MAC control PDU can indicate to a base station that resourceavailability corresponding to the access terminal is below a givenlevel, while the type 2 MAC control PDU can provide notification to thebase station that resource availability corresponding to the accessterminal is above the given level.

Pursuant to another example, an on-off MAC-based flow control scheme canbe utilized. Accordingly, a type 1 MAC control PDU that includes abinary value set to 0 can be generated when resource use of the accessterminal is determined to be above a first threshold, and a type 1 MACcontrol PDU that includes a binary value set to 1 can be generated whenthe resource use of the access terminal is determined to be below asecond threshold (e.g., the first threshold and the second threshold canbe the same or different, . . . ). Hence, setting the binary value to 0can yield notification to a base station that resource availabilityrelated to the access terminal is below a given level. Further, settingthe binary value to 1 can indicate to the base station that resourceavailability pertaining to the access terminal is above the given level.

By way of a further illustration, an up-down MAC-based flow controlscheme can be employed. An average detected downlink data transmissionrate experienced by the access terminal in a given time window can bedetermined (e.g., by the access terminal, . . . ). Moreover, a preferreddownlink data transmission rate for the access terminal can beidentified as a function of the monitored resource use (e.g., by theaccess terminal, . . . ). When the preferred downlink data transmissionrate is less than the average detected downlink data transmission rate,then a type 1 MAC control PDU that includes a first selected valuecorresponding to a percentage decrease from the average detecteddownlink data transmission rate to the preferred downlink datatransmission rate can be generated. Further, when the preferred downlinkdata transmission rate is greater than the average detected downlinkdata transmission rate, then a type 2 MAC control PDU that includes asecond selected value corresponding to a percentage increase from theaverage detected downlink data transmission rate to the preferreddownlink data transmission rate can be generated.

According to another example, a scaled access terminal capabilityMAC-based flow control scheme can be leveraged. Following this example,an updated downlink data transmission rate to be utilized by a basestation for subsequent transmission for the access terminal can bedetermined based upon the monitored resource use. Further, the updateddownlink data transmission rate can be compared to a previously signaleddownlink data transmission rate to be utilized by the base station. Whenthe updated downlink data transmission rate is less than the previouslysignaled downlink data transmission rate, then a type 1 MAC control PDUthat includes a first selected value corresponding to a percentagedecrease from the previously signaled downlink data transmission rate tothe updated downlink data transmission rate can be generated. Moreover,when the updated downlink data transmission rate is greater than thepreviously signaled downlink data transmission rate, then a type 2 MACcontrol PDU that includes a second selected value corresponding to apercentage increase from the previously signaled downlink datatransmission rate to the updated downlink data transmission rate can begenerated.

By way of further example, a PDCP-based flow control scheme can beutilized. For instance, at least one of a PDCP control PDU thatindicates a highest PDCP Sequence Number (SN), a highest Count-C whichincludes Hyper Frame Number (HFN) plus PDCP SN, or a part of a Count-C(e.g., lower 16 bits, . . . ) permitted to be transmitted by a basestation can be generated. According to another illustration, a PDCPcontrol PDU that indicates a maximum number of PDCP PDUs allowed to betransmitted by the base station in a Transmission Time Interval (TTI)can be generated. Pursuant to a further illustration, a PDCP control PDUthat switches an associated PDCP bearer between an on state and an offstate can be generated. In accordance with another example, a PDCPcontrol PDU that indicates an average rate at which PDCP can betransmitted by a base station can be generated.

At 706, the control PDU can be sent to a base station to manage adownlink data transmission rate. The control PDU can be transmitted onunscheduled uplink channels, for instance. Further, the downlink datatransmission rate can be altered by the base station in response to thesent control PDU.

With reference to FIG. 8, illustrated is a methodology 800 thatfacilitates providing downlink flow control in a wireless communicationenvironment. At 802, a level of resource utilization associated with anaccess terminal can be detected. For example, the resources can relateto processing speed, processor cycles, battery power, buffer size, busspeed, and so forth. The level of resource utilization can be comparedto a threshold (e.g., determine whether the level of resourceutilization is above or below the threshold, determined whetherresources of the access terminal are sufficient or insufficient tohandle a current traffic level received by the access terminal via thedownlink, . . . ). Additionally or alternatively, the level of resourceutilization can be monitored to recognize a percentage of an overallcapacity being currently employed (e.g., the percentage can correspondto one or more resources associated with the access terminal, . . . ).

At 804, a channel quality indicator (CQI) report that includes a valueselected as a function of the level of resource utilization associatedwith the access terminal can be generated. According to an exampleCQI-based flow control scheme, the value selected for inclusion in theCQI report can be a flow control code word that is reserved in CQI codespace to indicate a level of flow control. For instance, two flowcontrol code words can be reserved; a first one of these two flowcontrol code words can be included in the CQI report to reduce (e.g.,lower, stop, . . . ) a downlink data transmission rate utilized by abase station for the access terminal, while the second one of these twoflow control code words can be included in the CQI report to increase(e.g., raise, initiate, . . . ) a downlink data transmission rateemployed by the base station for the access terminal. Pursuant toanother illustration, one flow control code word can be reserved; thisflow control code word can be included in the CQI report to reduce(e.g., lower, stop, . . . ) a downlink data transmission rate for apredetermined period of time. Upon expiration of the predeterminedperiod of time, the downlink data transmission rate can increase (e.g.,raise, initiate, return to a previously employed level, . . . ).

By way of further example, a CQI-based flow control scheme can comprisegeneration of a CQI report that includes the value selected as afunction of the level of resource utilization associated with the accessterminal for transmission during a flow control reporting interval. Aperiodically occurring, predefined subset of CQI reporting intervals canbe used for flow control reporting (e.g., every Xth CQI reportinginterval can be a flow control reporting interval, where X can besubstantially any integer, . . . ). According to an example, during theflow control reporting interval, the value selected for inclusion in theCQI report can be a predetermined value when the level of resourceutilization exceeds a threshold (e.g., the access terminal is recognizedas being congested, . . . ), and the value selected for inclusion in theCQI report can be a measured CQI value dependent upon channel conditionswhen the level of resource utilization is below the threshold (e.g., theaccess terminal is recognized as being not congested, . . . ). Pursuantto a further example, during the flow control reporting interval, thevalue selected for inclusion in the CQI report can be a resourcedependent CQI value, which is a measured CQI value dependent uponchannel conditions reduced by a factor corresponding to the level ofresource utilization, when the access terminal is recognized as beingcongested. Following this example, when the access terminal is notcongested at a time period associated with this flow control reportinginterval, the measured CQI value can be the value selected for inclusionin the CQI report. Further, the resource dependent CQI value canindicate a degree of access terminal congestion.

At 806, the CQI report that includes the selected value can betransmitted to a base station to control a downlink data transmissionrate. The downlink data transmission rate can be adjusted by the basestation in response to the transmitted CQI report.

Now turning to FIG. 9, illustrated is a methodology 900 that facilitatescontrolling a downlink data transmission rate for an access terminalbased upon flow control feedback from the access terminal in a wirelesscommunication environment. At 902, a control protocol data unit (PDU)that provides flow control feedback can be received from an accessterminal. The control PDU can be a MAC control PDU, a PDCP control PDU,or the like. At 904, the control PDU can be analyzed to recognize theflow control feedback. For instance, the type of control PDU (e.g., type1 or type 2, . . . ), a value incorporated within the control PDU (e.g.,a binary value, an integer value, . . . ), a combination thereof, etc.can be identified to determine the flow control feedback. At 906, adownlink data transmission rate for the access terminal can be adjustedbased upon the flow control feedback provided by the control PDU.According to an illustration, downlink data transmission (e.g., exceptfor flows configured with a prioritized bit rate (PBR), . . . ) can bestarted or stopped based upon the identified type of the control PDU ora binary value recognized as being included in the control PDU. Pursuantto a further example, the downlink data transmission rate can beincreased or decreased based upon the identified type of the controlPDU, and a percentage change (e.g., increase or decrease, . . . ) forthe downlink data transmission rate can be recognized from an integervalue determined to be included in the control PDU.

Referring to FIG. 10, illustrated is a methodology 1000 that facilitatesutilizing flow control feedback to manage a downlink data transmissionrate for an access terminal in a wireless communication environment. At1002, a channel quality indicator (CQI) report that includes a valuecorresponding to flow control feedback can be received from an accessterminal. For instance, the CQI report that includes the valuecorresponding to the flow control feedback can be received during apredetermined flow control reporting interval (e.g., every Xth CQIreporting interval can be a flow control reporting interval, where X canbe substantially any integer, . . . ) or during substantially any CQIreporting interval. At 1004, the value included in the CQI report can beevaluated to determine the flow control feedback. For example, the valuecan be recognized as a flow control code word that is reserved in CQIcode space to indicate whether the access terminal is congested.According to another illustration, the value can be identified as aresource dependent CQI value. Further, the resource dependent CQI valuecan be reviewed to decipher a degree of congestion experienced by theaccess terminal. At 1006, a downlink data transmission rate for theaccess terminal can be adjusted based upon the flow control feedbackprovided by the CQI report. For instance, the adjusted downlink datatransmission rate can be utilized until expiration of a timer, receiptof subsequent flow control feedback, a combination thereof, and thelike.

It will be appreciated that, in accordance with one or more aspectsdescribed herein, inferences can be made regarding controlling downlinkdata transmission rates utilizing flow control feedback in a wirelesscommunication environment. As used herein, the term to “infer” or“inference” refers generally to the process of reasoning about orinferring states of the system, environment, and/or user from a set ofobservations as captured via events and/or data. Inference can beemployed to identify a specific context or action, or can generate aprobability distribution over states, for example. The inference can beprobabilistic—that is, the computation of a probability distributionover states of interest based on a consideration of data and events.Inference can also refer to techniques employed for composinghigher-level events from a set of events and/or data. Such inferenceresults in the construction of new events or actions from a set ofobserved events and/or stored event data, whether or not the events arecorrelated in close temporal proximity, and whether the events and datacome from one or several event and data sources.

According to an example, one or more methods presented above can includemaking inferences pertaining to determining trends in resourceutilization of an access terminal. By way of further illustration, aninference can be made related to determining a change in resourceutilization level associated with an access terminal that can resultfrom an adjustment in downlink data transmission rate. It will beappreciated that the foregoing examples are illustrative in nature andare not intended to limit the number of inferences that can be made orthe manner in which such inferences are made in conjunction with thevarious embodiments and/or methods described herein.

FIG. 11 is an illustration of an access terminal 1100 that generatesflow control feedback in a wireless communication system. Accessterminal 1100 comprises a receiver 1102 that receives a signal from, forinstance, a receive antenna (not shown), and performs typical actionsthereon (e.g., filters, amplifies, downconverts, etc.) the receivedsignal and digitizes the conditioned signal to obtain samples. Receiver1102 can be, for example, an MMSE receiver, and can comprise ademodulator 1104 that can demodulate received symbols and provide themto a processor 1106 for channel estimation. Processor 1106 can be aprocessor dedicated to analyzing information received by receiver 1102and/or generating information for transmission by a transmitter 1116, aprocessor that controls one or more components of access terminal 1100,and/or a processor that both analyzes information received by receiver1102, generates information for transmission by transmitter 1116, andcontrols one or more components of access terminal 1100.

Access terminal 1100 can additionally comprise memory 1108 that isoperatively coupled to processor 1106 and that can store data to betransmitted, received data, and any other suitable information relatedto performing the various actions and functions set forth herein. Memory1108, for instance, can store protocols and/or algorithms associatedwith monitoring utilization of resources associated with access terminal1100. Further, memory 1108 can store protocols and/or algorithms foryielding flow control feedback that can be sent from access terminal1100 over an uplink to a base station for controlling a downlink datatransmission rate.

It will be appreciated that the data store (e.g., memory 1108) describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable PROM (EEPROM), or flash memory. Volatile memorycan include random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).The memory 1108 of the subject systems and methods is intended tocomprise, without being limited to, these and any other suitable typesof memory.

Receiver 1102 is further operatively coupled to a resource monitor 1110and/or a flow control feedback generator 1112. Resource monitor 1110 canbe substantially similar to resource monitor 206 of FIG. 2. Moreover,flow control feedback generator 1112 can be substantially similar toflow control feedback generator 208 of FIG. 2. Although not depicted, itis to be appreciated that flow control feedback generator 1112 canfurther include a control PDU formatter, which can be substantiallysimilar to control PDU formatter 302 of FIG. 3, and/or a resource basedCQI report generator, which can be substantially similar to resourcebased CQI report generator 402 of FIG. 4. Resource monitor 1110 candetect a level of resource utilization associated with access terminal1100. For instance, resource monitor 1110 can determine whether or notaccess terminal 1100 is congested. Moreover, flow control feedbackgenerator 1112 can generate flow control feedback that can be sent to abase station to control a downlink data transmission rate. By way ofexample, the flow control feedback yielded by flow control feedbackgenerator 1112 can be a CQI report that includes a value selected as afunction of the resource utilization associated with access terminal1100. Pursuant to a further illustration, the flow control feedbackyielded by flow control feedback generator 1112 can be a control PDUgenerated based upon the resource utilization associated with accessterminal 1100. Access terminal 1100 still further comprises a modulator1114 and a transmitter 1116 that transmits the flow control feedback toa base station (e.g., a serving base station, . . . ). Although depictedas being separate from the processor 1106, it is to be appreciated thatresource monitor 1110, flow control feedback generator 1112 and/ormodulator 1114 can be part of processor 1106 or a number of processors(not shown).

FIG. 12 is an illustration of a system 1200 that utilizes obtained flowcontrol feedback to manage a downlink data transmission rate in awireless communication environment. System 1200 comprises a base station1202 (e.g., access point, . . . ) with a receiver 1210 that receivessignal(s) from one or more access terminals 1204 through a plurality ofreceive antennas 1206, and a transmitter 1224 that transmits to the oneor more access terminals 1204 through a transmit antenna 1208. Receiver1210 can receive information from receive antennas 1206 and isoperatively associated with a demodulator 1212 that demodulates receivedinformation. Demodulated symbols are analyzed by a processor 1214 thatcan be similar to the processor described above with regard to FIG. 11,and which is coupled to a memory 1216 that stores data to be transmittedto or received from access terminal(s) 1204 and/or any other suitableinformation related to performing the various actions and functions setforth herein. Processor 1214 is further coupled to a feedback analyzer1218 that can evaluate flow control feedback received from accessterminal(s) 1204. Moreover, base station 1202 can include a downlinkscheduler 1220 that can adjust a downlink data transmission rate basedupon the evaluated flow control feedback. It is contemplated thatfeedback analyzer 1218 can be substantially similar to feedback analyzer210 of FIG. 2 and/or downlink scheduler 1220 can be substantiallysimilar to downlink scheduler 212 of FIG. 2. Further, although notshown, it is to be appreciated that base station 1202 can furtherinclude a control PDU evaluator (e.g., which can be substantiallysimilar to control PDU evaluator 304 of FIG. 3, . . . ) and/or aresource based CQI report evaluator (e.g., which can be substantiallysimilar to resource based CQI report evaluator 404, . . . ). By way offurther illustration, downlink scheduler 1220 can provide information tobe transmitted to a modulator 1222. Modulator 1222 can multiplex a framefor transmission by a transmitter 1224 through antennas 1208 to accessterminal(s) 1204. Although depicted as being separate from the processor1214, it is to be appreciated that feedback analyzer 1218, downlinkscheduler 1220, and/or modulator 1222 can be part of processor 1214 or anumber of processors (not shown).

FIG. 13 shows an example wireless communication system 1300. Thewireless communication system 1300 depicts one base station 1310 and oneaccess terminal 1350 for sake of brevity. However, it is to beappreciated that system 1300 can include more than one base stationand/or more than one access terminal, wherein additional base stationsand/or access terminals can be substantially similar or different fromexample base station 1310 and access terminal 1350 described below. Inaddition, it is to be appreciated that base station 1310 and/or accessterminal 1350 can employ the systems (FIGS. 1-4, 11-12, and 14-17)and/or methods (FIGS. 7-10) described herein to facilitate wirelesscommunication there between.

At base station 1310, traffic data for a number of data streams isprovided from a data source 1312 to a transmit (TX) data processor 1314.According to an example, each data stream can be transmitted over arespective antenna. TX data processor 1314 formats, codes, andinterleaves the traffic data stream based on a particular coding schemeselected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot datausing orthogonal frequency division multiplexing (OFDM) techniques.Additionally or alternatively, the pilot symbols can be frequencydivision multiplexed (FDM), time division multiplexed (TDM), or codedivision multiplexed (CDM). The pilot data is typically a known datapattern that is processed in a known manner and can be used at accessterminal 1350 to estimate channel response. The multiplexed pilot andcoded data for each data stream can be modulated (e.g., symbol mapped)based on a particular modulation scheme (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM), etc.) selected forthat data stream to provide modulation symbols. The data rate, coding,and modulation for each data stream can be determined by instructionsperformed or provided by processor 1330.

The modulation symbols for the data streams can be provided to a TX MIMOprocessor 1320, which can further process the modulation symbols (e.g.,for OFDM). TX MIMO processor 1320 then provides N_(T) modulation symbolstreams to N_(T) transmitters (TMTR) 1322 a through 1322 t. In variousembodiments, TX MIMO processor 1320 applies beamforming weights to thesymbols of the data streams and to the antenna from which the symbol isbeing transmitted.

Each transmitter 1322 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel.Further, N_(T) modulated signals from transmitters 1322 a through 1322 tare transmitted from N_(T) antennas 1324 a through 1324 t, respectively.

At access terminal 1350, the transmitted modulated signals are receivedby N_(R) antennas 1352 a through 1352 r and the received signal fromeach antenna 1352 is provided to a respective receiver (RCVR) 1354 athrough 1354 r. Each receiver 1354 conditions (e.g., filters, amplifies,and downconverts) a respective signal, digitizes the conditioned signalto provide samples, and further processes the samples to provide acorresponding “received” symbol stream.

An RX data processor 1360 can receive and process the N_(R) receivedsymbol streams from N_(R) receivers 1354 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. RX dataprocessor 1360 can demodulate, deinterleave, and decode each detectedsymbol stream to recover the traffic data for the data stream. Theprocessing by RX data processor 1360 is complementary to that performedby TX MIMO processor 1320 and TX data processor 1314 at base station1310.

A processor 1370 can periodically determine which available technologyto utilize as discussed above. Further, processor 1370 can formulate areverse link message comprising a matrix index portion and a rank valueportion.

The reverse link message can comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message can be processed by a TX data processor 1338, whichalso receives traffic data for a number of data streams from a datasource 1336, modulated by a modulator 1380, conditioned by transmitters1354 a through 1354 r, and transmitted back to base station 1310.

At base station 1310, the modulated signals from access terminal 1350are received by antennas 1324, conditioned by receivers 1322,demodulated by a demodulator 1340, and processed by a RX data processor1342 to extract the reverse link message transmitted by access terminal1350. Further, processor 1330 can process the extracted message todetermine which precoding matrix to use for determining the beamformingweights.

Processors 1330 and 1370 can direct (e.g., control, coordinate, manage,etc.) operation at base station 1310 and access terminal 1350,respectively. Respective processors 1330 and 1370 can be associated withmemory 1332 and 1372 that store program codes and data. Processors 1330and 1370 can also perform computations to derive frequency and impulseresponse estimates for the uplink and downlink, respectively.

In an aspect, logical channels are classified into Control Channels andTraffic Channels. Logical Control Channels can include a BroadcastControl Channel (BCCH), which is a DL channel for broadcasting systemcontrol information. Further, Logical Control Channels can include aPaging Control Channel (PCCH), which is a DL channel that transferspaging information. Moreover, the Logical Control Channels can comprisea Multicast Control Channel (MCCH), which is a Point-to-multipoint DLchannel used for transmitting Multimedia Broadcast and Multicast Service(MBMS) scheduling and control information for one or several MTCHs.Generally, after establishing a Radio Resource Control (RRC) connection,this channel is only used by UEs that receive MBMS (e.g., oldMCCH+MSCH). Additionally, the Logical Control Channels can include aDedicated Control Channel (DCCH), which is a Point-to-pointbi-directional channel that transmits dedicated control information andcan be used by UEs having a RRC connection. In an aspect, the LogicalTraffic Channels can comprise a Dedicated Traffic Channel (DTCH), whichis a Point-to-point bi-directional channel dedicated to one UE for thetransfer of user information. Also, the Logical Traffic Channels caninclude a Multicast Traffic Channel (MTCH) for Point-to-multipoint DLchannel for transmitting traffic data.

In an aspect, Transport Channels are classified into DL and UL. DLTransport Channels comprise a Broadcast Channel (BCH), a Downlink SharedData Channel (DL-SDCH) and a Paging Channel (PCH). The PCH can supportUE power saving (e.g., Discontinuous Reception (DRX) cycle can beindicated by the network to the UE, . . . ) by being broadcasted over anentire cell and being mapped to Physical layer (PHY) resources that canbe used for other control/traffic channels. The UL Transport Channelscan comprise a Random Access Channel (RACH), a Request Channel (REQCH),a Uplink Shared Data Channel (UL-SDCH) and a plurality of PHY channels.

The PHY channels can include a set of DL channels and UL channels. Forexample, the DL PHY channels can include: Common Pilot Channel (CPICH);Synchronization Channel (SCH); Common Control Channel (CCCH); Shared DLControl Channel (SDCCH); Multicast Control Channel (MCCH); Shared ULAssignment Channel (SUACH); Acknowledgement Channel (ACKCH); DL PhysicalShared Data Channel (DL-PSDCH); UL Power Control Channel (UPCCH); PagingIndicator Channel (PICH); and/or Load Indicator Channel (LICH). By wayof further illustration, the UL PHY Channels can include: PhysicalRandom Access Channel (PRACH); Channel Quality Indicator Channel(CQICH); Acknowledgement Channel (ACKCH); Antenna Subset IndicatorChannel (ASICH); Shared Request Channel (SREQCH); UL Physical SharedData Channel (UL-PSDCH); and/or Broadband Pilot Channel (BPICH).

It is to be understood that the embodiments described herein can beimplemented in hardware, software, firmware, middleware, microcode, orany combination thereof. For a hardware implementation, the processingunits can be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described herein, or a combination thereof.

When the embodiments are implemented in software, firmware, middlewareor microcode, program code or code segments, they can be stored in amachine-readable medium, such as a storage component. A code segment canrepresent a procedure, a function, a subprogram, a program, a routine, asubroutine, a module, a software package, a class, or any combination ofinstructions, data structures, or program statements. A code segment canbe coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters, or memorycontents. Information, arguments, parameters, data, etc. can be passed,forwarded, or transmitted using any suitable means including memorysharing, message passing, token passing, network transmission, etc.

For a software implementation, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes can be storedin memory units and executed by processors. The memory unit can beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

With reference to FIG. 14, illustrated is a system 1400 that enablesproviding flow control feedback to a base station using control protocoldata units (PDUs) in a wireless communication environment. For example,system 1400 can reside within an access terminal. It is to beappreciated that system 1400 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). System 1400 includes a logical grouping 1402 of electricalcomponents that can act in conjunction. For instance, logical grouping1402 can include an electrical component for tracking resourceutilization associated with an access terminal 1404. Moreover, logicalgrouping 1402 can include an electrical component for yielding a controlprotocol data unit (PDU) as a function of the resource utilizationassociated with the access terminal 1406. Further, logical grouping 1402can include an electrical component for transmitting the control PDU toa base station to control a downlink data transmission rate 1408.Additionally, system 1400 can include a memory 1410 that retainsinstructions for executing functions associated with electricalcomponents 1404, 1406, and 1408. While shown as being external to memory1410, it is to be understood that one or more of electrical components1404, 1406, and 1408 can exist within memory 1410.

Turning to FIG. 15, illustrated is a system 1500 that enables yieldingflow control feedback to a base station using channel quality indicator(CQI) reports in a wireless communication environment. System 1500 canreside within an access terminal, for instance. As depicted, system 1500includes functional blocks that can represent functions implemented by aprocessor, software, or combination thereof (e.g., firmware). System1500 includes a logical grouping 1502 of electrical components that canact in conjunction. Logical grouping 1502 can include an electricalcomponent for detecting resource utilization associated with an accessterminal 1504. Moreover, logical grouping 1502 can include an electricalcomponent for yielding a channel quality indicator (CQI) report thatincludes a value selected as a function of the resource utilizationassociated with the access terminal 1506. Further, logical grouping 1502can include an electrical component for sending the CQI report thatincludes the selected value to a base station to control a downlink datatransmission rate 1508. Additionally, system 1500 can include a memory1510 that retains instructions for executing functions associated withelectrical components 1504, 1506, and 1508. While shown as beingexternal to memory 1508, it is to be understood that electricalcomponents 1504, 1506, and 1508 can exist within memory 1510.

With reference to FIG. 16, illustrated is a system 1600 that enablesadjusting a downlink data transmission rate utilizing flow controlfeedback in a wireless communication environment. For example, system1600 can reside at least partially within a base station. It is to beappreciated that system 1600 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). System 1600 includes a logical grouping 1602 of electricalcomponents that can act in conjunction. For instance, logical grouping1602 can include an electrical component for obtaining a controlprotocol data unit (PDU) that provides flow control feedback from anaccess terminal 1604. Moreover, logical grouping 1602 can include anelectrical component for evaluating the control PDU to identify the flowcontrol feedback 1606. Further, logical grouping 1602 can include anelectrical component for altering a downlink data transmission rate forthe access terminal based upon the flow control feedback provided by thecontrol PDU 1608. Additionally, system 1600 can include a memory 1610that retains instructions for executing functions associated withelectrical components 1604, 1606, and 1608. While shown as beingexternal to memory 1610, it is to be understood that one or more ofelectrical components 1604, 1606, and 1608 can exist within memory 1610.

With reference to FIG. 17, illustrated is a system 1700 that enablesaltering a downlink data transmission rate employing flow controlfeedback in a wireless communication environment. For example, system1700 can reside at least partially within a base station. It is to beappreciated that system 1700 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). System 1700 includes a logical grouping 1702 of electricalcomponents that can act in conjunction. For instance, logical grouping1702 can include an electrical component for obtaining a channel qualityindicator (CQI) report that includes a value corresponding to flowcontrol feedback from an access terminal 1704. Further, logical grouping1702 can include an electrical component for analyzing the valueincluded in the CQI report to identify the flow control feedback 1706.Moreover, logical grouping 1702 can include an electrical component formodifying a downlink data transmission rate for the access terminalbased upon the flow control feedback provided by the CQI report 1708.Additionally, system 1700 can include a memory 1710 that retainsinstructions for executing functions associated with electricalcomponents 1704, 1706, and 1708. While shown as being external to memory1710, it is to be understood that one or more of electrical components1704, 1706, and 1708 can exist within memory 1710.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.

What is claimed is:
 1. A method, comprising: detecting a level ofresource utilization of a hardware resource on an access terminal;determining, based upon the level of resource utilization, that thehardware resource cannot support a downlink data transmission rate;generating a channel quality indicator report that includes a selectedvalue selected as a function of the level of resource utilization of thehardware resource on the access terminal, wherein the channel qualityindicator report comprises a request to reduce the downlink datatransmission rate to temporarily mitigate hardware resource requirementsfor the access terminal; selecting a first flow control code word forinclusion in the channel quality indicator report to reduce the downlinkdata transmission rate employed by a base station, the first flowcontrol code word being reserved in a channel quality indicator codespace; selecting a second flow control code word for inclusion in thechannel quality indicator report to increase the downlink datatransmission rate employed by the base station, the second flow controlcode word being reserved in the channel quality indicator code space;and transmitting the channel quality indicator report that includes theselected value to the base station.
 2. The method of claim 1, furthercomprising selecting a flow control code word for inclusion in thechannel quality indicator report to reduce the downlink datatransmission rate employed by the base station for a predeterminedperiod of time, the flow control code word being reserved in the channelquality indicator code space.
 3. The method of claim 1, furthercomprising transmitting the channel quality indicator report thatincludes the selected value to the base station during a correspondingflow control reporting interval, wherein every Xth channel qualityindicator reporting interval is a flow control reporting interval and Xis an integer.
 4. The method of claim 3, further comprising: selecting apredetermined value as the value for inclusion in the channel qualityindicator report to be transmitted during the corresponding flow controlreporting interval when the level of resource utilization exceeds athreshold; and selecting a measured channel quality indicator value thatis dependent upon channel conditions as the value for inclusion in thechannel quality indicator report to be transmitted during thecorresponding flow control reporting interval when the level of resourceutilization is below the threshold.
 5. The method of claim 3, furthercomprising: selecting a resource dependent channel quality indicatorvalue, which is a measured channel quality indicator value that isdependent upon channel conditions reduced by a factor corresponding tothe level of resource utilization, as the value for inclusion in thechannel quality indicator report to be transmitted during thecorresponding flow control reporting interval when the level of resourceutilization exceeds a threshold; and selecting the measured channelquality indicator value as the value for inclusion in the channelquality indicator report to be transmitted during the corresponding flowcontrol reporting interval when the level of resource utilization isbelow the threshold.
 6. A wireless communications apparatus, comprising:a memory that retains instructions related to: detecting a level ofresource utilization of a hardware resource on an access terminal,determining, based upon the level of resource utilization, that thehardware resource cannot support a downlink data transmission rate,generating a channel quality indicator report that includes a selectedvalue selected as a function of the level of resource utilization of thehardware resource on the access terminal, wherein the channel qualityindicator report comprises a request to reduce the downlink datatransmission rate to temporarily mitigate hardware resource requirementsfor the access terminal, selecting a first flow control code word forinclusion in the channel quality indicator report to reduce the downlinkdata transmission rate employed by a base station, selecting a secondflow control code word for inclusion in the channel quality indicatorreport to increase the downlink data transmission rate employed by thebase station, the first flow control code word and the second flowcontrol code word being reserved in a channel quality indicator codespace, and transmitting the channel quality indicator report thatincludes the selected value to the base station; and a processor,coupled to the memory, configured to execute the instructions retainedin the memory.
 7. The wireless communications apparatus of claim 6,wherein the memory further retains instructions related to selecting aflow control code word for inclusion in the channel quality indicatorreport to reduce the downlink data transmission rate employed by thebase station for a predetermined period of time, the flow control codeword being reserved in the channel quality indicator code space.
 8. Thewireless communications apparatus of claim 6, wherein the memory furtherretains instructions related to transmitting the channel qualityindicator report that includes the selected value to the base stationduring a corresponding flow control reporting interval, wherein everyXth channel quality indicator reporting interval is a flow controlreporting interval and X is an integer.
 9. The wireless communicationsapparatus of claim 8, wherein the memory further retains instructionsrelated to: selecting a predetermined value as the value for inclusionin the channel quality indicator report to be transmitted during thecorresponding flow control reporting interval when the level of resourceutilization exceeds a threshold, and selecting a measured channelquality indicator value that is dependent upon channel conditions as thevalue for inclusion in the channel quality indicator report to betransmitted during the corresponding flow control reporting intervalwhen the level of resource utilization is below the threshold.
 10. Thewireless communications apparatus of claim 8, wherein the memory furtherretains instructions related to: selecting a resource dependent channelquality indicator value, which is a measured channel quality indicatorvalue that is dependent upon channel conditions reduced by a factorcorresponding to the level of resource utilization, as the value forinclusion in the channel quality indicator report to be transmittedduring the corresponding flow control reporting interval when the levelof resource utilization exceeds a threshold, and selecting the measuredchannel quality indicator value as the value for inclusion in thechannel quality indicator report to be transmitted during thecorresponding flow control reporting interval when the level of resourceutilization is below the threshold.
 11. A wireless communicationsapparatus, comprising: means for detecting a level of resourceutilization of a hardware resource on an access terminal; means fordetermining, based upon the level of resource utilization, that thehardware resource cannot support a downlink data transmission rate;means for yielding a channel quality indicator report that includes aselected value selected as a function of the level of resourceutilization of the hardware resource on the access terminal, wherein thechannel quality indicator report comprises a request to reduce thedownlink data transmission rate to temporarily mitigate hardwareresource requirements for the access terminal; means for selecting afirst flow control code word for inclusion in the channel qualityindicator report to reduce the downlink data transmission rate employedby a base station, the first flow control code word being reserved in achannel quality indicator code space; means for selecting a second flowcontrol code word for inclusion in the channel quality indicator reportto increase the downlink data transmission rate employed by the basestation, the second flow control code word being reserved in the channelquality indicator code space; and means for sending the channel qualityindicator report that includes the selected value to the base station.12. The wireless communications apparatus of claim 11, furthercomprising means for selecting a flow control code word for inclusion inthe channel quality indicator report to reduce the downlink datatransmission rate employed by the base station for a predeterminedperiod of time, the flow control code word being reserved in the channelquality indicator code space.
 13. The wireless communications apparatusof claim 11, further comprising means for sending the channel qualityindicator report that includes the selected value to the base stationduring a corresponding flow control reporting interval, whereinreporting intervals included in a predetermined subset of channelquality indicator reporting intervals are used as a flow controlreporting intervals.
 14. The wireless communications apparatus of claim13, further comprising: means for selecting a predetermined value as thevalue for inclusion in the channel quality indicator report to be sentduring the corresponding flow control reporting interval when the levelof resource utilization exceeds a threshold; and means for selecting ameasured channel quality indicator value that is dependent upon channelconditions as the value for inclusion in the channel quality indicatorreport to be sent during the corresponding flow control reportinginterval when the level of resource utilization is below the threshold.15. The wireless communications apparatus of claim 13, furthercomprising: means for selecting a resource dependent channel qualityindicator value, which is a measured channel quality indicator valuethat is dependent upon channel conditions reduced by a factorcorresponding to the level of resource utilization, as the value forinclusion in the channel quality indicator report to be sent during thecorresponding flow control reporting interval when the level of resourceutilization exceeds a threshold; and means for selecting the measuredchannel quality indicator value as the value for inclusion in thechannel quality indicator report to be sent during the correspondingflow control reporting interval when the level of resource utilizationis below the threshold.
 16. A non-transitory computer-readable mediumcomprising: code for detecting a level of resource utilization of ahardware resource on an access terminal; code for determining, basedupon the level of resource utilization, that the hardware resourcecannot support a downlink data transmission rate; code for generating achannel quality indicator report that includes a selected value selectedas a function of the level of resource utilization of the hardwareresource on the access terminal, wherein the channel quality indicatorreport comprises a request to reduce the downlink data transmission rateto temporarily mitigate hardware resource requirements for the accessterminal; code for selecting a first flow control code word forinclusion in the channel quality indicator report to reduce the downlinkdata transmission rate employed by a base station, the first flowcontrol code word being reserved in a channel quality indicator codespace; code for selecting a second flow control code word for inclusionin the channel quality indicator report to increase the downlink datatransmission rate employed by the base station, the second flow controlcode word being reserved in the channel quality indicator code space;and code for transmitting the channel quality indicator report thatincludes the selected value to the base station.
 17. The non-transitorycomputer-readable medium of claim 16, further comprising code forselecting a flow control code word for inclusion in the channel qualityindicator report to reduce the downlink data transmission rate employedby the base station for a predetermined period of time, the flow controlcode word being reserved in the channel quality indicator code space.18. The non-transitory computer-readable medium of claim 16, furthercomprising code for transmitting the channel quality indicator reportthat includes the selected value to the base station during acorresponding flow control reporting interval, wherein every Xth channelquality indicator reporting interval is a flow control reportinginterval and X is an integer.
 19. The non-transitory computer-readablemedium of claim 18, further comprising: code for selecting apredetermined value as the value for inclusion in the channel qualityindicator report to be transmitted during the corresponding flow controlreporting interval when the level of resource utilization exceeds athreshold; and code for selecting a measured channel quality indicatorvalue that is dependent upon channel conditions as the value forinclusion in the channel quality indicator report to be transmittedduring the corresponding flow control reporting interval when the levelof resource utilization is below the threshold.
 20. The non-transitorycomputer-readable medium of claim 18, further comprising: code forselecting a resource dependent channel quality indicator value, which isa measured channel quality indicator value that is dependent uponchannel conditions reduced by a factor corresponding to the level ofresource utilization, as the value for inclusion in the channel qualityindicator report to be transmitted during the corresponding flow controlreporting interval when the level of resource utilization exceeds athreshold; and code for selecting the measured channel quality indicatorvalue as the value for inclusion in the channel quality indicator reportto be transmitted during the corresponding flow control reportinginterval when the level of resource utilization is below the threshold.